State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
National Plant Gene Research Center, Beijing, China.
PLoS Pathog. 2018 Feb 23;14(2):e1006909. doi: 10.1371/journal.ppat.1006909. eCollection 2018 Feb.
Insect vitellogenin (Vg) has been considered to be synthesized in the fat body. Here, we found that abundant Vg protein is synthesized in Laodelphax striatellus hemocytes as well. We also determined that only the hemocyte-produced Vg binds to Rice stripe virus (RSV) in vivo. Examination of the subunit composition of L. striatellus Vg (LsVg) revealed that LsVg was processed differently after its expression in different tissues. The LsVg subunit able to bind to RSV exist stably only in hemocytes, while fat body-produced LsVg lacks the RSV-interacting subunit. Nymph and male L. striatellus individuals also synthesize Vg but only in hemocytes, and the proteins co-localize with RSV. We observed that knockdown of LsVg transcripts by RNA interference decreased the RSV titer in the hemolymph, and thus interfered with systemic virus infection. Our results reveal the sex-independent expression and tissue-specific processing of LsVg and also unprecedentedly connect the function of this protein in mediating virus transmission to its particular molecular forms existing in tissues previously known as non-Vg producing.
昆虫卵黄蛋白原（Vg）被认为是在脂肪体中合成的。在这里，我们发现大量的 Vg 蛋白也在直纹稻虱的血细胞中合成。我们还确定，只有血细胞产生的 Vg 与体内的水稻条纹病毒（RSV）结合。对直纹稻虱 Vg（LsVg）的亚基组成的研究表明，在不同组织中表达后，LsVg 的处理方式不同。能够与 RSV 结合的 LsVg 亚基在血细胞中稳定存在，而脂肪体产生的 LsVg 缺乏与 RSV 相互作用的亚基。若虫和雄性直纹稻虱个体也合成 Vg，但仅在血细胞中合成，且这些蛋白与 RSV 共定位。我们观察到，通过 RNA 干扰敲低 LsVg 转录本会降低血淋巴中的 RSV 滴度，从而干扰系统性病毒感染。我们的结果揭示了 LsVg 的性别独立表达和组织特异性加工，并且以前所未有的方式将该蛋白在介导病毒传播中的功能与其在先前被认为是非 Vg 产生组织中存在的特定分子形式联系起来。
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